Having determined (see Progress Report) that polymorphonuclear neutrophils following a thermal burn are the source of collagenase in vitamin A-deficient corneas, our next step will be to determine the least trauma, involving the epithelium only, that will provoke the release of collagenase from corneas of vitamin A-deficient rats. We are currently testing a scraping technique, and the application of heptanol. We also wish to improve on our assay of collagenase, by using labeled collagen instead of the capillary assay. Finally, we are determining the in vitro formation of a specific formation of a specific glycoprotein, following vitamin A-treatment, of thermally burned corneas in vitro.